Abstract: Objective To establish the transgenic cell line of hOSM gene and observe its effect on the proliferation of umbilical cord blood(UCB)CD34+ HSPC as a feeder layer. Methods A transgenic cell line was established by molecular biology method and CD34+ HSPCs were separated by magnetic-activated cell sorting. After 7 days' co-culture, the amplification effect was evaluated by flow cytometry. Then CD34+ cells stained by CFDA SE were injected into the SCID mice with sublethally irradiation and the effect of transplation was observed by fluorescence microscopy and RT-PCR. Results The number of CD34+ cells increased by 9.6 times and the expression rate of homing-ralated molecules was still higher than 50%. Four weeks after transplantion, CD34+ cells were found in bone marrow of SCID mice. Conclusion The transgenic cell line of hOSM gene as a feeder layer can effectively amplify UCB CD34+ HSPC ex vivo and suppress its differentiation. Meanwhile, they have high transplantion efficacy and haematogenesis activity.